Semiconductor sensor devices are known in the art. FIG. 8 shows a schematic cross section through a known semiconductor sensor device, this semiconductor sensor device representing a microelectromechanical module 51 comprising a sensor housing 117 and comprising a sensor 52.
A sensor region 113 is formed by a cutout 57 in a plastic housing composition 56 and has flat conductor ends 111 surrounding a central position 115 on the bottom 128 of the cutout. A further part 120 of the flat conductors 59 projects from the sensor housing 117 and forms external contacts 121 corresponding to the sensor region 113. Various sensors 52 can be arranged into a sensor housing 117 of this type on the central position 115, the central position 115 having a metallic chip island 122 on the bottom 128.
A pressure sensor 124 produced on a silicon base 125 is fixed on the chip island 122 and reacts to pressure fluctuations which are transmitted to the pressure-sensitive region of the pressure sensor 124 by a rubber-elastic plastic composition 58. The flexure of a silicon diaphragm 126 brings about a capacitive change between the upper side of the silicon diaphragm 126 and a rigid metal-plated glass plate 130 arranged above the latter, so that pressure fluctuations can be detected via the capacitive change. For this purpose, the electrodes of the pressure sensor 124 are connected to a control and evaluation semiconductor chip 53 via bonding connections 110 and corresponding flat conductors 59.
A semiconductor sensor device of this type has the disadvantage that the silicon base 125 of the silicon diaphragm 126 is fixed on a chip island 122 which, for its part, is held by the bottom 128 made from a plastic housing composition 56. Since the housing bottom 128 made from the plastic housing composition 56 has a significantly larger coefficient of thermal expansion than the silicon base 125 of the silicon diaphragm 126, there is the risk of thermal stresses between the material of the silicon base 125 and the material of the plastic housing composition 56 prestressing the silicon diaphragm in such a way that the sensor characteristic is impaired.
If the pressure measurements are not based on a capacitive coupling, but rather on a diaphragm equipped with piezoelements, then thermomechanical stresses have an even more significant effect on the measurement signals since piezoelements of this type generate erroneous signals in the event of thermomechanical stresses.
Furthermore, the known sensor device of this micromechanical module 51 has the disadvantage that the rubber-elastic plastic composition 58 above the pressure-sensitive region and within the cutout 57 has a variable contour that is not unambiguously defined, which likewise impairs the sensor characteristic, especially as the sensor sensitivity depends on the thickness of the rubber-elastic plastic composition 58 arranged above the diaphragm 126.
When fitting the bonding connections 110, too, mechanical forces act on the sensor chip, whereby the characteristic curve may be impaired undesirably, in part also uncontrollably. Even if sensitive sensor areas, as in the prior art, are covered with soft rubber-elastic materials, the dispensing processes involved are critical, especially as the sensitivity of the sensors depends appreciably on the height of the material dispensed over a sensor diaphragm.